Explained: Bandgap
Why do some materials work well for making solar cells or light-emitting diodes (LEDs), while other materials don’t? One key factor is having the right bandgap.In a nutshell, bandgaps have to do with how electrons behave and what it takes to get them excited. Electrons are the subatomic particles that carry a negative charge, and that surround the nucleus of an atom. When a bunch of electrons all move together in the same direction, they form an electric current.Electrons in an atom can be thought of as being somewhere in an array of possible “states” — which include their energy level, momentum and spin — with different probabilities of being in a given state. Two electrons can’t be in the same state at the same time — that is, at least one of these variables must differ. Some particular states are possible, and some are forbidden by the laws of...